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A topic for amusement Debunking Time Travel

  1. Sep 23, 2009 #1
    I don't know if this has been discussed before, but I offer this paradox to debunk time travel.

    If time travel was possible, given an infinite amount of time from the point of its discovery and perfection; then someone eventually would have traveled back in time and made its existence known to people in the past.
    To assume that only those responsible enough to avoid tampering with the past would use this ability is contrary to human nature as a whole. I argue that eventually someone would use the ability to travel in time to their own advantage.

    This is my argument against the potential for time travel.


    Disclaimer. This is not a major concern in my life so please don't feel that you are arguing with me as much as my paradox.

    Happy Debunking.
  2. jcsd
  3. Sep 23, 2009 #2
    Feed it back for confirmation:

    You wish to argue that time travel is impossible, because if it were, someone from the future wioulld haven (would+have+will; time travel grammar is confusing), traveled back in time for a purpose that benefits only them, and thus we willen would (will+would) of somehow known about it?

    Unknown. We yet do not understand how time itself works.
    There are many examples in science fiction.

    Back to the Future, the future can be altered by your actions in the past. Only those aware it are those who traveled though. So in this scenario, even if someone whialld (will+had) already traveled back and done something, we'd be unaware.

    Star Trek: Enterprise, the Temporal War seems to show that time is very flexible, even if the past is altered, it may not be permanent and can be re-altered.

    In short, I don't think this debunks time travel as it assumes a specific functionality of time for which we have no idea how it truly works.
  4. Sep 23, 2009 #3
    I guess for clarification that I am arguing that someone would eventually travel to the past/present (yes time travel word tense is hard) with the claim that they have traveled from the future and have the means to prove it.
    The argument that we would not know if someone had changed things is valid unless the person's intent was to make the fact known.
    I guess the Back to the Future example would be that not only would you travel back, but you would tell everyone that you did. Not only would you take advantage of the immediate for-knowledge, but you would establish yourself as a Messiah of sorts.

    I'll add a few more parameters. (I know that this is kind of a difficult topic to discuss, but its just for fun.)
    - The assumption is made that you can travel with whatever you want to bring with you
    e.g. no Terminator naked guy/electric ball scenario.
    - There is only a single thread of existence.
    e.g. changing something in the past does not start a new thread of existence. For example you make a change to the placement of a stop sign in the past, and an alternate reality is started where from that point, on a separate future is created after car wreck occurred at the original position of the stop sign. (This should eliminate most Star Treck explainations for the effects of time travel)
  5. Sep 23, 2009 #4
    There are two ways that time travel could be possible and still avoid your paradox.

    First, there could be "an ensemble of parallel universes/timelines" such that when the traveler goes back in time, any actions that take place do so in a parallel universe. Meanwhile, the existence of the travelers original universe/timeline is unaltered.

    Second, the nature of time travel may prohibit you from traveling back in time further than the point at which the time machine was invented. So there's no going back to 1930 and killing Hitler, no killing your grandad or any of that. You couldn't travel back into history because there weren't any time machines back then.
  6. Sep 23, 2009 #5
    John Titor

    Whose to say that any of the historical spiritual or religious leaders of the world cultures did not do just this? There are plenty of cultural references to strange people arriving, possessing knowledge unknown at the times and assisting the locals in developing advanced societies. Aztec, Mayans, Egyptians, etc...
  7. Sep 23, 2009 #6


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    Niven's Law: If the universe of discourse permits the possibility of time travel and of changing the past, then no time machine will be invented in that universe.

    He even wrote a short story about it.
  8. Sep 23, 2009 #7
    I guess firstly this would then debunk the possibility of traveling withen a single dimension as the paradox is confined to a single dimension. This would imply that if time travel was possible it would have to be something to a transition to between dimensions instead of "taking a step back."

    In regards to your second point I guess that this would imply that a "time machine" is tied to itself. That the device creates its own manipulation of physics or creates its own law. When you enter this device you are able to deliver yourself within the confines of the machine. You could describe suspended animation as a form of one way time travel by this standard. You are allowed to pass forward in time but now back.

    This is an interesting point, some people could have gone back to ancient times and tried to have an impact on society in a time period that they would be more accepting of a new message. I wonder if man has a predisposition to disbelieving someone who says they are traveling through time so no has tried to make the claim that has been believed.

    If Jesus returns in a pod of sorts or in 2012 some Mayan deity shows up in a fancy machine (or stark naked in a ball of lighting) we should be suspicious.
  9. Sep 23, 2009 #8
    Time police. :wink:
  10. Sep 23, 2009 #9
    I thought about how I didn't think time travel would be possible because someone would have went back and prevented 9/11. That would have been the easiest event to prevent.
    But then I thought maybe there's some crazier stuff happening in the future that they're using all the time machines to prevent.
  11. Sep 23, 2009 #10
    Just as you could not apply 21st century ethics to a 9th century conflict, do not believe that our current social conflicts would be of any concern to someone in the 42nd century. Cause and effect. We cannot late fore-when if the events of 9/11 wioll haven be (had refer to Dr. Dan Streetmentioner's Time Traveler's Handbook of 1001 Tense Formations) an effect to lead to world peace in the 23rd century.
  12. Sep 23, 2009 #11

    Ivan Seeking

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    Some of the real models for time machines suggest that one could only travel back in time to the point that the machine was turned on.

    Obviously the extreme Many-Worlds models make the paradoxes of time travel moot.
  13. Sep 23, 2009 #12
    That is a very good point. If time travel was invented far enough into the future, the events of our time could be considered insignificant/unimportant to possible needs of the distant future.

    An interesting side note... If you were to time travel on a planet a hundred-thousand (+) light years away, what time would they be in, in relation to our own planet?
  14. Sep 23, 2009 #13

    Ivan Seeking

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    How do we know that history hasn't already been changed many times?
  15. Sep 23, 2009 #14
    Ah, that is the source of my paradox...
    The argument is that if it was possible, given enough time eventually someone would make it known to us here in our time. Of course, it is assumed that this person would make it known to us and have the means to prove it.
    Simply stated, given enough time this would have to happen.

    *And in answer to your tag Ivan I think the problem is that the extremists are primarily the only ones who bother to get involved with politics : ) *
  16. Sep 23, 2009 #15

    Ivan Seeking

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    Maybe it has happened many times and the time cops came back and changed it again.

    Too many assumptions to be made.

    Again, there are other possible escapes, like some variations of the Many Worlds Theory.

    As for politics, it is everyone's civic duty to be involved. Don't live with your head in a hole or you might get bit in the butt! :biggrin: As they say, all politics are local.
    Last edited: Sep 23, 2009
  17. Sep 23, 2009 #16
    If time travel were possible, you should go back in time and prevent yourself from posting this thread. However, if time travel is really impossible, at least outside the future cone of the invention, then this thread is worthy of keeping open. Therefore, time travel is impossible, at least in the intersection of the future cone of this discussion creation and the past cone of the invention of the time machine. What !?
  18. Sep 23, 2009 #17
    1. Experts have been wrong before, are likely wrong today, and will continue to be wrong in the future.
    2. Whatever the mind of a sentient being can conceive and believe, it can achieve.
    3. Any technology, no matter how primitive, is magic to those who don't understand it.

    Although the means in which to achieve time travel are not currently understood, time travel is likely a possibility, though we may not recognize it as such even if observed.
  19. Sep 23, 2009 #18
  20. Sep 23, 2009 #19


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    You made the "rule" to start with that we have only one single thread of existence, and that may be the source of the problem for a time traveler changing the past...

    Ivan asked the question how would we know that history had been changed, and the answer is that with a single thread we cannot know. If a time-traveller goes back in time and changes something, the change will continue through the thread to his time and he will be unaware of the change; he won't even have the thought to travel back in time and change whatever it is he went back to change in the first place, because in changing the past he will have also changed himself (this goes back to the single-string time traveller's paradox: what happens when a time traveller kills his father?).

    It seems that someone could come back and predict something that was not due to human interaction such as a volcanic eruption, or asteroid strike. The fact that no one has done this means either that time travel through this model is not possible, or that there is nothing worth predicting to us right now.
  21. Sep 23, 2009 #20
    lol, this is really a good point... We should try to keep the thread open lest I forget to go tell myself to eat my own words.

    True if a sufficient regulatory force existed to keep people from taking advantage of the ability to time travel existed perhaps we are already being interfered with on a daily basis.

    Perhaps "miracles" are a result of the influence of future beings who felt a need to make a change.

    Is someone in the future deciding what needs to be changed and what doesn't? Is someone in the future permitted to make these very important decisions.
  22. Sep 23, 2009 #21

    Chi Meson

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    As far as I recall from my studies long ago...

    Kip Thorne created a plausible model for "time travel" through the quantum foam. It is essentially approaching the realm of "impossible" to accomplish due to the enormous quantity of negative energy density required to expand a "foam bubble" large enough to fit through.

    Even then, the "portal" would be fixed at that point in time. Its not so much the invention of the time machine itself, but the point in space-time that the opening was created. The "tube," of sorts, could be stretched from that point allowing transit between the future and the initial point.

    That's from a very old memory. Sounded iffy 15 or 20 years ago, and it looks more suspect even now, but hey, it's Kip! I'm not gonna argue. (I don't really understand it, honestly)
  23. Sep 23, 2009 #22
    Good point, if a time traveler goes back and changes something he would essentially remove his need to go and thus have never left... Another paradox.

    It could also be argued that the human race is wiped out before time travel is ever invented/discovered...quantumthere'dededupon-at
  24. Sep 23, 2009 #23
    My memory of Kip et al conclusions
    • you need an exotic form of matter, whose pressure exceed its own energy content, to ensure the stability of the wormhole. We have not the faintest idea whether such an exotic form of matter is possible even in principle
    • even if you come up with your exotic matter, the wormhole is still unstable : spontaneous quantum fluctuations will amplify themselves, blowing up your wormhole in less than a Planck time, as measured by the observer attempting to go through the wormhole...
  25. Sep 23, 2009 #24
    It should be very possible to travel into the future from the perspective of the traveler certaintly. "Simply" traveling at the speed of light away from the earth for a time and coming back should provide a certain form of forward time travel. A way to see what your
    great(x10^6)grand kids are doing with themselves. This is assuming Einstein was totally right.
  26. Sep 23, 2009 #25

    Chi Meson

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    Sounds risky. You first!
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